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Please silence your cell phones

Please silence your cell phones. AMERICA VOTES!. Adric Riedel ASTR8600 2008 02 05. 12% of nearby stars are K stars (68% are M stars) K stars are the brightest dwarfs visible to the unaided eye Most of the red color of Pop II stars is K giants

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Please silence your cell phones

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  1. Please silence your cell phones

  2. AMERICA VOTES! Adric Riedel ASTR8600 2008 02 05

  3. 12% of nearby stars are K stars (68% are M stars) • K stars are the brightest dwarfs visible to the unaided eye • Most of the red color of Pop II stars is K giants • All K star temperatures range between roughly 5180K and 3850K • Marked by the first appearance of TiO lines • Spectra no longer approximate blackbody • Not well studied (even the Kaler book has a lot of filler) • K dwarfs could have tidally unlocked planets in their habitable zones • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Commonality of K stars 3

  4. Luminosity range is smaller for K stars: -9.2 (RW Ceph, K0Ia-0) to 8.46 (HIP 20302, K9V) • Luminosity Class VII (White Dwarfs) first appears in K stars (15.43 (GJ 223.2, DZ9) may actually be in the M star range.) • Subdwarfs are still distinct in luminosity from Main Sequence stars in the K region. • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Commonality of K stars 4

  5. Not all luminosity classes or subtypes are equally meaningful. • Keenan, 1985: • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Spectral Features of K stars 5

  6. “The letter K represents spectra of the later second type, or intermediate between the second and third types. The letter K may be briefly described as representing the spectra in which the bands K and H, the band G, and the line 4227.0 are the most conspicuous features, and in which the end of the shorter wave length is faint, and the distribution of light is not uniform with different parts of the spectrum. The hydrogen lines in this class are fainter than numerous solar lines” • 'Second' and 'Third' are remnants of an earlier system • 4227.0Å is CaI • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited The Henry Draper Catalog (1901) 6

  7. Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited MKK System (1943) 7

  8. “The G-band continues to increase in strength until the early K-type stars (about K2) and then begins to fade. The Ca I 4227 line grows gradually in strength until the early K stars, and then becomes dramatically stronger by mid-K... The temperature type may be estimated with precision, even in metal-weak stars by using the ratio of the Cr I 4254 line with the two neighboring Fe I lines at 4250 and 4260... Notice that the Cr I line (which arises from a low-lying level) becomes stronger in ratio with the two flanking Fe I lines, being clearly stronger than both by K5. • In the K-type dwarfs, the spectral type may be estimated from the ratio of Ca I 4227 to Fe I 4383, in the sense that Ca I/Fe I grows toward later types. By M0, bands due to TiO become visible in the spectrum, and these strengthen quite dramatically toward later types; by M4.5 they dominate the spectrum.” • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Richard Gray's Spectral Atlas 8

  9. Classified between 6000A and 9000A, instead of 3800A-4900A • Boundary between K and M set based on continuum slope between 7700A and 8100A • Ten types defined, like Cannon (1901), but unlike the MKK system (0,2,3,5) or the revised MK system (added K7 halftype) • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Beaulieu et al. (2008, in prep) 9

  10. G band breaks up in cooler subtypes • Ca I 4227 Å increases in strength with cooler subtypes • Ca II H and K lines weaken with cooler subtypes • Ba II visible in giant and supergiant atmospheres (Boeshaar, private communication)... but also more prominent in Barium stars regardless of type. • If you look in any atlas of spectral types, you will find the feature at 4077 Å marked as an ultimate line of Sr II, and used as an important criterion in estimating luminosity of the stars. Actually, however, this line is blended with rather strong lines of Y I, La II, Dy II and Fe I ( 4078). The iron line is not sensitive to luminosity, while abundance of the heavy elements is an important factor in determining the strength of the other contributors. (Keenan, 1984) • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Spectral Features of K stars 10

  11. Keenan-McNeil Spectral Atlas • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Spectral Features of K stars 11

  12. Keenan-McNeil Spectral Atlas • Heavily studied in the blue part of the spectrum • the 'G' band visible in K stars and hotter (where visible) • Inversions in the Calcium K bands • The 'CN' break at 4215A is stronger for supergiants (though this depends on abundances of Carbon and Nitrogen) • Color-magnitude diagrams (also useful for multiplicity) • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Weeding out luminosity classes 12

  13. epsilon Pegasi: K2 Ib • (Alberio A: K3 II) • (Pollux: K0 III & planet) • Aldebaran: K5 III • Arcturus: K1 III • Alpha Centauri B: K1 V • epsilon Eridani: K2 V & planet • 61 Cygni A&B K5 V & K7 V • GJ 223.2: DZ9 (VII) • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Our Famous K Star Contenders 13

  14. SSS plates assembled with Aladin Skyview • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited GJ 223.2: DZ 9 white dwarf 14

  15. Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited GJ 223.2: DZ 9 white dwarf 15

  16. http://www.seds.org/messier/Pics/More/m15cnoao.jpg • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited epsilon Pegasi: K2 Ib supergiant 16

  17. Second brightest star in Pegasus, after Alpha Andromeda (!) (http://www.astro.uiuc.edu/~kaler/sow/enif.html) • 150 Rsun, 10 Msun, 6700 Lsun, variable with erratic behavior • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited epsilon Pegasi: K2 Ib supergiant 17

  18. http://www.df9cy.de/image_astro/moon_aldebaran.jpg • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Aldebaran: K5 III giant 18

  19. Giant star, has changed to helium fusion • 40 Rsun, 350 Lsun, variable star • 13th brightest star in the sky • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Aldebaran: K5 III giant 19

  20. NASA, ESA, and G. Bacon (STScI) • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Epsilon Eridani: K2 V dwarf 20

  21. Nearby young dwarf K star • 0.85 Msun, 0.84 Rsun, 0.27 Lsun. ~600 Myr old (http://www.solstation.com/stars/eps-erid.htm) • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited epsilon Eridani: K2 V dwarf 21

  22. RECONS • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Alpha Centauri B: K0 V dwarf 22

  23. 21st brightest star in the sky • ~17” away from the third brightest star in the sky • ~6 Gyr old • Only 1.338 parsecs away • 0.92 Msun, 0.51 Lsun • SUN 14 39 35.1 -60 50 14.0 3.724 284.8 3 b GJ0559B V 1.34 K0 V CNS91 RECONS ALPHA CEN B, I dare you! • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Alpha Centauri B: K0 V dwarf 23

  24. Lowell Observatory, 1916 & 1951 photos(Possibly assembled by Guy K. McArthur)‏ Via solstation.com • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited 61 Cygni A&B: K5 V & K7 V 24

  25. 0.15 and 0.09 Solar Luminosities; 0.6 and 0.5 solar masses • Highest proper motion stars known in the 1800s • First stars with a known parallax (2/3 arcsec, by Bessel) • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited 61 Cygni AB (K5V, K7V)‏ 25

  26. The Morgan & Keenan C,N, and S types extend into K as well, both as giants and dwarfs (Green, P. 1996, IAU symposium) • S stars are thought to be halfway between main-sequence stars and C class Carbon Stars, with extra Yttrium and Zirconium in their upper atmospheres. • C dwarfs are mass transfer recipients, and are fairly common • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Various unusual oddballs: C and S stars 26

  27. Note the extreme VO and ZrO absorption bands that reduce the 'continuum' to spikes. • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited S stars 27

  28. C2 bands, CN bands, and apparently presence of C13 isotopes • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited C stars 28

  29. America's New K Star!

  30. Green, P.J. 1996, IAU #177 invited talk • Keenan, P.C. 1985, Calibration of Fundamental Stellar Quantities, 111, 121 • Keenan, P.C. 1984, The MK Process and Stellar Classification, 29 • Turnshek, et al. “An Atlas of Digital Spectra of Cool Stars” 1985 • Star parameters from James Kaler's “Stars”: http://www.astro.uiuc.edu/~kaler/sow/sowlist.html • Politician images courtesy of Google Images • Title • K star properties • K star features • Descriptions • Luminosity classes • Examples: • Class VII • Class I • Class III • Class V • S and C stars • Works Cited Works Cited 30

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